Battery pack and method for producing battery pack

ABSTRACT

A battery element is housed and sealed in a package body, and further, packed together with a connecting board and a frame by the package body. A laminate material for sealing the battery element is used as an outer package material of a battery pack. Thus, the increase of volume for the pack is reduced as much as possible.

RELATED APPLICATION DATA

This application is a divisional of U.S. patent application Ser. No.10/834,532, filed Apr. 29, 2004, now U.S. Pat. No. 7,348,762 theentirety of which is incorporated herein by reference to the extentpermitted by law. The present invention claims priority to Japanesepatent application No. 2003-126714 filed in the Japanese Patent Officeon May 1, 2003, the entirety of which also is incorporated by referenceherein to the extent permitted by law.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a battery pack and a method forproducing it in which the volume of an outer package part is suppressedas much as possible.

2. Description of the Related Art

In recent years, a demand for an information device such as a note booktype personal computer, a mobile communication device such as a portabletelephone and a portable electronic device such as a video camera hasbeen rapidly increased. As a power source of such electronic devices, asealed type small secondary battery such as a nickel-cadmium battery, anickel-metal hydride battery, a lithium-ion battery has been frequentlyemployed. The characteristics of the lithium-ion secondary battery suchas high voltage, high energy density and lightweight have been made agood use of among them, so that the lithium-ion battery has beenemployed in a variety of fields.

Especially, to cope with the leakage of liquid which causes a problemwhen liquid type electrolyte solution is used, for instance, a batteryusing a gel polymer film obtained by impregnating polymer withnon-aqueous electrolyte solution as an electrolyte, or what is called apolymer lithium-ion secondary battery using a completely solid stateelectrolyte are proposed.

In the above-described battery, as shown in FIG. 1, a single cell 301formed by laminating battery elements is ordinarily housed in a pair ofupper and lower plastic cases 303 and 304 together with a connectingboard 302 having a protective circuit or terminals to obtain a batterypack 300 (for instance, see Japanese Patent Application Laid-Open No.2002-8606).

However, in the above-described structure, the thickness of the plasticcases 303 and 304 needs to be 0.3 to 0.4 mm. Further, when a double sidetape or a tolerance for fixing is taken into consideration, thethickness of about 0.8 to 1 mm is increased to the thickness of thebattery. In an outer peripheral direction, a configuration forperforming an ultrasonic welding to the upper and lower plastic cases303 and 304 is needed. Accordingly, the thickness of about 0.7 mm isrequired therefor. Therefore, the battery pack 300 needs to increase itsvolume about 1.3 to 1.4 times as much as the battery.

SUMMARY OF THE INVENTION

The present invention is proposed by considering the above-describedcircumstances and it is an object of the present invention to provide abattery pack in which the increase of volume for the pack is decreasedas much as possible without deteriorating a mechanical strength and thereliability of terminals and a method for producing the battery pack.

A battery pack of the present invention comprises: a battery elementhaving a cathode, an anode and polymer electrolyte, terminals beingdrawn from the cathode and the anode, respectively; a package bodyhaving a first area in which a housing recessed part for housing thebattery element is formed, a second area formed continuously to thefirst area and a third area provided continuously to the second area soas to be substantially perpendicular to the first area; a frame disposedin the periphery of the housing recessed part in which the batteryelement is housed; and a connecting board disposed in the frame to whichthe terminals are connected and having a terminal part electricallyconnected to an external device.

In the battery pack according to the present invention, the batteryelement is housed in the recessed part. The second area located in aside opposite to a side from which the terminals of the housed batteryelement are drawn is bent relative to the first area to cover a firstsurface of the battery element exposed outside therewith and unite thefirst area to the second area. The terminals of the battery elementhoused in the housing recessed part and covered with the second area areconnected to the connecting board. The frame is disposed in theperiphery of the housing recessed part in which the battery element ishoused. The connecting board is provided in the frame. The third area ofthe package body is bent relative to the second area. A second surfaceside opposite to the first surface of the battery element housed in thehousing recessed part of the first area and covered with the first areaand the second area is covered with the third area and the third area isunited to the first area.

In the battery pack according to the present invention as describedabove, a laminate material of the battery element is used as an outerpackage material of the pack so that volume efficiency is improved.

Further, in a method for producing a battery pack that comprises: abattery element having a cathode, an anode and polymer electrolyte,terminals being drawn from the cathode and the anode, respectively; afirst package body having a housing recessed part for housing thebattery element and a uniting piece provided in the periphery of thehousing recessed part; a second package body having at least a firstarea with which a first surface of the battery element housed in thehousing recessed part which is exposed outside is covered and a secondarea with which a second surface side opposite to the first surface iscovered; a frame disposed in the periphery of the housing recessed partin which the battery element is housed; and a connecting board disposedin the frame to which the terminals are connected and having a terminalpart electrically connected to an external device, according to thepresent invention, the method comprises the steps of housing the batteryelement in the housing recessed part of the first package body; coveringthe first surface of the battery element exposed outside with the firstarea of the second package body to unite the uniting piece to the firstarea; connecting the terminals of the battery element housed in thehousing recessed part and covered with the first area of the secondpackage body to the connecting board, disposing the frame in theperiphery of the battery element and providing the connecting board inthe frame; bending the second area of the second package body relativeto the first area to cover the second surface side opposite to the firstsurface of the battery element housed in the housing recessed part ofthe first package body and covered with the first area with the secondarea and uniting the first package body to the second area of the secondpackage body.

In the method for producing the battery pack according to the presentinvention as described above, the laminate film of the battery elementis used as an outer package material, so that volume efficiency can beimproved.

Further, a battery pack according to the present invention comprises: abattery element having a cathode, an anode and polymer electrolyte,terminals being drawn from the cathode and the anode, respectively; afirst package body having a housing recessed part for housing thebattery element and a uniting piece provided in the periphery of thehousing recessed part; a second package body having at least a firstarea with which a first surface of the battery element housed in thehousing recessed part which is exposed outside is covered and a secondarea with which a second surface side opposite to the first surface iscovered; a frame disposed in the periphery of the housing recessed partin which the battery element is housed; and a connecting board disposedin the frame to which the terminals are connected and having a terminalpart electrically connected to an external device.

In the battery pack of the present invention, the battery element ishoused in the housing recessed part of the first package body. The firstsurface of the battery element exposed outside is covered with the firstarea of the second package body. The uniting piece is united to thefirst area. The terminals of the battery element housed in the housingrecessed part and covered with the first area of the second package bodyare connected to the connecting board. The frame is disposed in theperiphery of the housing recessed part in which the battery element ishoused and the connecting board is disposed in the frame. The secondarea of the second package body is bent relative to the first area. Thesecond surface side opposite to the first surface of the battery elementhoused in the housing recessed part of the first package body andcovered with the first area is covered with the second area to unite thefirst package body to the second area of the second package body.

In the battery pack according to the present invention as describedabove, a laminate material of the battery element is used as an outerpackage material of the pack so that volume efficiency is improved.

Further, a method for producing a battery pack according to the presentinvention comprises: a first step of housing a battery element having acathode, an anode and polymer electrolyte, terminals being drawn fromthe cathode and the anode, respectively in a housing recessed part of afirst package body having the housing recessed part for housing thebattery element and a uniting piece provided in the periphery of thehousing recessed part; a second step of covering a first surface of thebattery element housed in the housing recessed part which is exposedoutside with a first area of a second package body having at least thefirst area with which the first surface is covered and a second areawith which a second surface side opposite to the first surface iscovered and uniting the uniting piece to the first area; a third step ofconnecting the terminals of the battery element housed in the housingrecessed part and covered with the first area of the second package bodyto a connecting board having a terminal part electrically connected toan external device, disposing a frame in the periphery of the housingrecessed part in which the battery element is housed and providing theconnecting board on the frame; a fourth step of bending the second areaof the second package body relative to the first area and covering thesecond surface side opposite to the first surface of the battery elementhoused in the housing recessed part of the first package body andcovered with the first area with the second area; and a fifth step ofuniting the first package body to the second area of the second packagebody.

In the method for producing the battery pack according to the presentinvention as described above, the laminate film of the battery elementis used as an outer package material, so that volume efficiency can beimproved.

Further, a battery pack according to the present invention comprises: abattery element having a cathode, an anode and polymer electrolyte,terminals being drawn from the cathode and the anode, respectively; afirst package body having a housing recessed part for housing thebattery element and a uniting piece provided in the periphery of thehousing recessed part; a second package body having a first area withwhich a first surface of the battery element housed in the housingrecessed part of the first package body which is exposed outside iscovered and a second area provided continuously to one side of the firstarea and harder than the first package body; a frame disposed in theperiphery of the housing recessed part of the first package body inwhich the battery element is housed; and a connecting board disposed inthe frame to which the terminals are connected.

In the battery pack of the present invention, the battery element ishoused in the housing recessed part of the first package body. The firstsurface of the battery element exposed outside from the housing recessedpart is covered with the first area of the second package body byuniting the uniting piece of the first package body to the first area ofthe second package body to draw outside the terminals of the batteryelement. The terminals of the battery element housed in the housingrecessed part of the first package body and covered with the first areaof the second package body are connected to the connecting board. Theframe is disposed in the periphery of the housing recessed part of thefirst package body in which the battery element is housed and theconnecting board is disposed in the frame. The second area of the secondpackage body is bent back to a second surface side opposite to the firstsurface of the battery element housed in the housing recessed part ofthe first package body relative to the first area united to the unitingpiece of the first package body by using the one short side of the firstarea as a supporting point to cover the housing recessed part of thefirst package body with the second area of the second package body andunite the second area of the second package body to the frame.

In the battery pack according to the present invention as describedabove, the second package body for packing the battery element isemployed as a pack outer package material, so that volume efficiency isimproved. In the battery pack, since the second package body as the packouter package material is harder than the first package body, thedeformation and deterioration of the battery element due to an externalimpact such as an impact owing to falling or the generation of flaws onthe second package body is suppressed to prevent an external appearancefrom being poor. Further, in the battery pack, when the housing part ofthe first package body is covered with the second area of the secondpackage body, the second area is bent back by using the one short sideof the first area as a supporting point. Thus, the bent part of thesecond package body is decreased to suppress the generation of wrinklesor the like in the bent part.

Further, a method for producing a battery pack comprises: a first stepof housing a battery element having a cathode, an anode and polymerelectrolyte, terminals being drawn from the cathode and the anode,respectively in a housing recessed part of a first package body havingthe housing recessed part for housing the battery element and a unitingpiece provided in the periphery of the housing recessed part; a secondstep of covering a first surface of the battery element with a firstarea of a second package body having the first area with which the firstsurface of the battery element housed in the housing recessed part ofthe first package body which is exposed outside the battery element iscovered and a second area provided continuously to one side of the firstarea and harder than the first package body so as to draw the terminalsof the battery element outside and uniting the uniting piece of thefirst package body to the first area of the second package body; a thirdstep of connecting the terminals of the battery element housed in thehousing recessed part of the first package body and covered with thefirst area of the second package body to a connecting board, disposing aframe in the periphery of the housing recessed part of the first packagebody in which the battery element is housed and disposing the connectingboard in the frame and a fourth step of bending the second area of thesecond package body back to a second surface side opposite to the firstsurface of the battery element housed in the housing recessed part ofthe first package body relative to the first area united to the unitingpiece of the first package body by using the one short side of the firstarea as a supporting point to cover the housing recessed part of thefirst package body with the second area of the second package body andunite the second area of the second package body to the frame.

In the method for producing the battery pack according to the presentinvention as described above, the second package body for packing thebattery element is employed as a pack outer package material, so thatvolume efficiency is improved. In the method for producing the batterypack, since the second package body as the pack outer package materialis harder than the first package body, a battery pack in which thedeformation and deterioration of the battery element due to an externalimpact such as an impact owing to falling or the generation of flaws onthe second package body is suppressed is obtained. Further, in themethod for producing the battery pack, when the housing part of thefirst package body is covered with the second area of the second packagebody, the second area is bent back by using the one short side of thefirst area as a supporting point. Thus, the bent part of the secondpackage body is decreased to suppress the generation of wrinkles or thelike in the bent part.

Further, a battery pack according to the present invention comprises: abattery element having a cathode, an anode and polymer electrolyte,terminals being drawn from the cathode and the anode, respectively; afirst package body having a housing recessed part for housing thebattery element and a uniting piece provided in the periphery of thehousing recessed part; a second package body with which a first surfaceof the battery element housed in the housing recessed part of the firstpackage body which is exposed outside is covered and which is harderthan the first package body; a third package body with which the housingrecessed part of the first package body in a second surface sideopposite to the first surface of the battery element is covered andwhich is harder than the first package body; a frame disposed in theperiphery of the housing recessed part of the first package body inwhich the battery element is housed; and a connecting board disposed inthe frame to which the terminals are connected.

In the battery pack of the present invention, the battery element ishoused in the housing recessed part of the first package body. The firstsurface of the battery element exposed outside from the housing recessedpart is covered with the second package body so that the terminals ofthe battery element are drawn outside by uniting the uniting piece ofthe first package body to the second package body. The terminals of thebattery element housed in the housing recessed part and covered with thesecond package body are connected to the connecting board. The frame isdisposed in the periphery of the housing recessed part of the firstpackage body in which the battery element is housed and the connectingboard is disposed in the frame. The housing recessed part of the firstpackage body in the second surface side of the battery element iscovered with the third package body and the frame provided in theperiphery of the battery element is united to the third package body.

In the battery pack according to the present invention as describedabove, the second package body for packing the battery element isemployed as a pack outer package material, so that volume efficiency isimproved. In the battery pack, since the second package body and thethird package body as the pack outer package materials are harder thanthat of the first package body, the deformation and deterioration of thebattery element due to an external impact such as an impact owing tofalling or the generation of flaws on the second package body and thethird package body is suppressed to prevent an external appearance frombeing poor. Further, in the battery pack, since the outer package bodyis composed of two of the second package body and the third packagebody, the generation of wrinkles or the like is suppressed to improvethe external appearance.

Further, a method for producing a battery pack according to the presentinvention comprises: a first step of housing a battery element having acathode, an anode and polymer electrolyte, terminals being drawn fromthe cathode and the anode, respectively in a housing recessed part of afirst package body having the housing recessed part for housing thebattery element and a uniting piece provided in the periphery of thehousing recessed part; a second step of covering a first surface of thebattery element housed in the housing recessed part of the first packagebody which is exposed outside with a second package body harder than thefirst package body to unite the uniting piece of the first package bodyto the second package body; a third step of connecting the terminals ofthe battery element housed in the housing recessed part of the firstpackage body and covered with the second package body to a connectingboard, disposing a frame in the periphery of the housing recessed partof the first package body in which the battery element is housed andproviding the connecting board between the frame and the batteryelement; and a fourth step of covering the housing recessed part of thefirst package body in a second surface side opposite to the firstsurface of the battery element with a third package body harder than thefirst package body to unite the frame provided in the periphery of thehousing recessed part of the first package body in which the batteryelement is housed to the third package body.

In the method for producing the battery pack according to the presentinvention as described above, the second package body and the thirdpackage body for packing the battery element are employed as pack outerpackage materials, so that volume efficiency is improved. In the methodfor producing the battery pack, since the second package body and thethird package body as the pack outer package materials are harder thanthat of the first package body, the deformation and deterioration of thebattery element due to an external impact such as an impact owing tofalling or the generation of flaws on the second package body and thethird package body is suppressed to prevent an external appearance frombeing poor. Further, in the method for producing the battery pack, sincethe outer package body is composed of two of the second package body andthe third package body, a battery pack is obtained in which thegeneration of wrinkles or the like in the second package body and thethird package body is suppressed to improve the external appearance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing the structure of a usualbattery pack using a plastic case.

FIG. 2 is a perspective view showing one structural example of a batterypack to which the present invention is applied.

FIG. 3 is a sectional view taken along a line X₁-X₂ in FIG. 2.

FIG. 4 is a perspective view showing a state in which a battery elementis housed in a housing recessed part.

FIG. 5 is a sectional view showing the laminated structure of a packagebody.

FIG. 6 is a perspective view showing a state that a frame is disposed inthe periphery of the housed battery element.

FIG. 7 is a perspective view showing the structure of the frame.

FIG. 8 is a sectional view taken along a line X₃-X₄ in FIG. 7.

FIG. 9 is a sectional view showing a state that the frame is disposed inthe periphery of the housed battery element.

FIG. 10 is a perspective view showing one structural example of abattery pack to which the present invention is applied.

FIG. 11 is a sectional view taken along a line X₅-X₆ in FIG. 10.

FIG. 12 is a perspective view showing a state in which a battery elementis housed in a housing recessed part.

FIG. 13 is a sectional view showing the laminated structure of a packagebody.

FIG. 14 is a plan view showing a state that a second package body issuperposed on a first package body.

FIG. 15 is a perspective view showing a state that a frame is disposedin the periphery of the housed battery element.

FIG. 16 is a sectional view showing a state that the frame has beendisposed in the periphery of the housed battery element.

FIG. 17 is a sectional view showing a state that the periphery of thebattery element is covered with a second package body.

FIG. 18 is a sectional view showing a state that the periphery of thebattery element has been covered with the second package body.

FIG. 19 is a perspective view showing one structural example of abattery pack to which the present invention is applied.

FIG. 20 is a sectional view taken along a line X₇-X₈ in FIG. 19.

FIG. 21 is a perspective view showing the structure of a frame.

FIG. 22 is a sectional view taken along a line X₉-X₁₀ in FIG. 19.

FIG. 23 is a perspective view showing a state that a battery element ishoused in a housing recessed part.

FIG. 24 is a sectional view showing the laminated structure of a firstpackage body.

FIG. 25 is a perspective view of a second package body.

FIG. 26 is a sectional view showing the laminated structure of a secondpackage body.

FIG. 27 is a perspective view showing a state that the second packagebody is superposed on the first package body.

FIG. 28 is a sectional view showing a state that a frame is disposed inthe periphery of the housed battery element.

FIG. 29 is an exploded perspective view showing a state that the frameand a fixing member are arranged in the periphery of the housed batteryelement.

FIG. 30 is a sectional view showing a state that the periphery of thebattery element is covered with the second package body.

FIG. 31 is a perspective view showing one structural example of abattery pack to which the present invention is applied.

FIG. 32 is a sectional view taken along a line X₁₁-X₁₂ in FIG. 31.

FIG. 33 is a perspective view showing a state that a battery element ishoused in a housing recessed part.

FIG. 34 is a perspective view showing a state that a second package bodyis superposed on a first package body.

FIG. 35 is a sectional view showing a state that the second package bodyis superposed on the first package body.

FIG. 36 is an exploded perspective view showing a state that a frame isarranged in the periphery of the battery element housed in the housingrecessed part.

FIG. 37 is a sectional view taken along a line X₁₃-X₁₄ in FIG. 31.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, referring to the accompanying drawings, embodiments of a batterypack according to the present invention will be described below.

First Embodiment

FIG. 2 is a perspective view showing one structural example of a batterypack to which the present invention is applied. FIG. 3 is a sectionalview taken along a line X₁-X₂ in FIG. 2. FIGS. 4 to 9 are diagrams forexplaining a method for producing the battery pack.

The battery pack 1 comprises a battery element 2, a connecting board 3,a frame 4 and a package body 5. The battery element 2 is accommodatedand sealed in the package body 5 and further packed together with theconnecting board 3 and the frame 4 by the package body 5.

In the battery element 2, an elongated cathode and an elongated anodeare laminated through a polymer electrolyte layer and/or a separator anda laminated body is coiled in a longitudinal direction. A cathodeterminal 21 and an anode terminal 22 are respectively drawn outside fromthe cathode and the anode.

The cathode has a cathode active material layer formed on an elongatedcathode current collector and the polymer electrolyte layer formed onthe cathode active material layer. Further, the anode has an anodeactive material layer formed on an elongated anode current collector andthe polymer electrolyte layer formed on the anode active material layer.The cathode terminal 21 and the anode terminal 22 are respectivelyconnected to the cathode current collector and the anode currentcollector.

The cathode can be formed by using metallic oxide, metallic sulfide orspecific polymer as a cathode active material depending on a kind of adesired battery. For instance, when a lithium-ion battery is formed, alithium composite oxide including, as the cathode active material,Li_(x)MO₂ (In the formula, M represents one or more kinds of transitionmetals. x is different depending on charging and discharging states ofthe battery and ordinarily 0.05 or higher and 1.10 or lower.) or thelike may be employed. As the transition metals M forming the lithiumcomposite oxide, Co, Ni, Mn, etc. are preferable. As specific examplesof the lithium composite oxide, LiCoO₂, LiNiO₂, LiNi_(y)Co_(1-y)O₂ (Inthe formula, y is larger than 0 and smaller than 1.), LiMn₂O₄, etc. maybe exemplified. These lithium composite oxides can generate high voltageso that they are excellent cathode active materials in view of energydensity. Further, as the cathode active materials, the metallic sulfidesor the metallic oxides including no lithium such as TiS₂, MoS₂, NbSe₂,V₂O₅, etc. may be employed. In the cathode, a plurality of kinds of thecathode active materials may be used together. Further, when theabove-described cathode active materials are used to form the cathode, awell-known conductive agent or a binding agent may be added thereto.

As an anode material, a material capable of being doped with lithium andbeing dedoped from lithium may be used. For instance, carbon materialssuch as non-graphitizable carbonaceous materials or graphitizablematerials may be used. More specifically, carbon materials such aspyrocarbons, coke (pitch coke, needle coke, petroleum coke), graphites,vitreous carbons, organic polymer compound sintered bodies (carbonizedmaterials obtained by sintering phenolic resins, furan resins, etc. atsuitable temperature), carbon fibers, activated carbon, etc. may beemployed. In addition thereto, as the materials capable of being dopedwith lithium and dedoped from lithium, polymers such as polyacetylene,polypyrrole or oxides such as SnO₂ may be used. When the anode is formedfrom these materials, a well-known binding agent may be added thereto.

The polymer electrolyte is obtained by containing gel electrolyte formedby mixing a polymer material, electrolyte solution and electrolyte saltin polymer. The polymer material has a feature soluble in theelectrolyte solution. The polymer materials include silicon gel, acrylgel, acrylonitrile gel, modified polyphosphazene polymer, polyethyleneoxide, polypropylene oxide and composite polymers, bridged polymers ormodified polymers of them, etc. As fluorine polymers, for instance,various kinds of polymer materials such as poly (vinylidene fluoride),poly (vinylidene fluoride-co-hexafluoropropylene) or poly (vinylidenefluoride-co-trifluoroethylene) and mixtures of them may be used.

An electrolyte solution component is capable of dispersing theabove-described polymer materials. As an aprotic solvent, for instance,ethylene carbonate (EC), propylene carbonate (PC) or butylene carbonate(BC) or the like is used. As the electrolyte salt, electrolyte saltsoluble in the solvent is employed and is formed by combining cationwith anion. As the cation, alkali metals or alkaline earth metals areused. As the anions, Cl⁻, Br⁻, I⁻, SCN⁻, ClO₄ ⁻, BF₄ ⁻, PF₆ ⁻, CF₃SO₃ ⁻,etc. are employed. As the electrolyte salt, specifically, lithiumhexafluorophosphate or lithium tetrafluoroborate is used with a solubleconcentration the electrolyte solution.

The package body 5 for accommodating the battery element 2 therein is,as shown in FIG. 4, formed in a substantially L-shape having a firstarea 51 with a substantially rectangular form, a second area 52 with asubstantially rectangular form longitudinally continuous to the firstarea 51 and a third area 53 with a substantially rectangular formcontinuous to the direction of a short side of the second area 52 so asto be substantially perpendicular to the first area 51. In the firstarea 51, a housing recessed part 54 in which the battery element 2 ishoused is previously formed.

The package body 5 has, as shown in FIG. 5, a laminated structure inwhich a polypropylene (PP) layer 55, an aluminum (Al) layer 56 and anylon layer (Ny) 57 are laminated in order from inside. Here, thealuminum layer 56 prevents water from entering an inner part. Thepolypropylene layer 55 prevents the deterioration of the polymerelectrolyte and serves as a uniting surface of the package body 5. Thatis, when the package body 5 is united, the polypropylene layers 55 areopposed to each other and heat-sealed at about 170° C. The nylon layer57 gives a prescribed strength to the package body 5.

The structure of the package body 5 is not limited to theabove-described structure and a laminate film having various kinds ofmaterials and laminated structures may be employed. Further, a unitingmethod thereof is not limited to a heat sealing method.

As the materials for forming the package body, for instance, aluminum,polyethylene terephthalate (PET), cast polypropylene (CPP), acidmodified polypropylene, ionomer, etc. may be exemplified.

In the present invention, a laminate material for sealing the batteryelement 2 is used also as an outer package material of the battery pack1. Thus, a plastic case is not required to improve volume efficiency.

Initially as shown by an arrow mark A in FIG. 4, the battery element 2is accommodated in the housing recessed part 54 provided in the firstarea 51 of the package body 5. At this time, the terminal side of thebattery element 2 is disposed to be opposite to the second area 52.

Then, as shown by an arrow mark B, the second area 52 is bent to thefirst area 51 in a bending line 5 a. Thus, the first surface of thebattery element 2 housed in the housing recessed part which is exposedoutside is covered with the second area 52.

Then, the first area 51 is united to the second area 52. The uniting iscarried out by allowing the polypropylene layer sides of the first area51 and the second area 52 to be opposed to each other and heat-sealingthem at about 170° C.

At this time, as shown in FIG. 9, a pressure reducing pump 80 is used toreduce pressure as well as a uniting. The battery element 2 is coveredwith and sealed by the first area 51 and the second area 52 due to asuction force. At this time, the cathode terminal 21 and the anodeterminal 22 of the battery element 2 are sandwiched in between theuniting surfaces of the first area 51 and the second area 52 to be drawnoutside the package body 5.

As shown in FIG. 9, the pressure is reduced to suck the first area 51.Thus, the battery element 2 accommodated in the housing recessed part 54is drawn to have a substantially trapezoidal form in which a secondsurface side as the bottom surface side of the housing recessed part 54is small and the first surface side as an opening side is large.

Subsequently, the cathode terminal 21 and the anode terminal 22 areconnected to a terminal part 31 of the connecting board 3. The terminalpart 31 is electrically connected to an external device. Further, in theconnecting board 3, a protective circuit chip 32 or the like isarranged.

As shown by a central arrow mark C in FIG. 6, in the periphery of thebattery element 2 accommodated in the housing recessed part 54 of thefirst area 51 and covered and sealed with the second area 52, the frame4 is disposed from the first area 51 side. The connecting board 3 havingthe terminal part 31 to which the cathode terminal 21 and the anodeterminal 22 are connected is fitted to the frame 4.

The frame 4 is a frame member having a size corresponding to the outerform of the battery element 2 as shown in FIGS. 6 and 7. The frame 4comprises a front wall part 4 a disposed in the terminal side of thebattery element 2, a rear wall part 4 b disposed in a side opposite tothe terminals of the battery element 2 and side wall parts 4 c disposedin the side surface parts of the battery element 2. The frame 4 isarranged in the periphery of the battery element 2 to protect thebattery element 2 from an impact due to, for instance, falling. Theframe 4 may be formed with various kinds of plastic materials.Especially, the same material of the uniting surface of the package body5 as polypropylene, that is, polypropylene or a material having the samemelting point as that of polypropylene are preferably exemplified.

As described above, the battery element 2 has a substantiallytrapezoidal shape in section under a reduced pressure. As shown in FIG.9, the side wall parts 4 c of the frame 4 are arranged in space partsformed in the peripheral edge parts of the second surface side of thebattery element 2. Thus, a dead space can be effectively utilized tomore improve volume efficiency.

The parts of the side walls 4 c opposed to the battery element 2 arepreferably formed in R shapes. Thus, the strength and impact resistanceof the frame 4 can be increased.

In the front wall part 4 a of the frame 4 corresponding to the terminalside of the battery element 2, the connecting board 3 is disposed and anopening part 41 is formed. The opening part 41 allows the terminal part31 of the connecting board 3 to face outside. The connecting board 3 isdisposed in the frame 4 while the terminal part 31 faces outside fromthe opening part 41. The terminal part 31 facing outside from theopening part 41 is electrically connected to the external device. Inthis example, three opening parts 41 are provided. These opening parts41 can be used for, for instance, the cathode terminal, the anodeterminal and other information terminal. However, the use of theopenings is not limited thereto.

Further, in the frame 4, engaging members 42 having substantiallytriangular forms in section are disposed and the connecting board 3 isengaged with the engaging members 42 to be arranged in the frame 4.

An enlarged view of the engaging part is shown in FIG. 8. The engagingmember 42 has a substantially right-angled triangle form including asubstantially vertical surface 42 a in the front wall surface side 4 aand an inclined surface 42 b inclined toward an opening side. When theconnecting board 3 is disposed in the frame 4, the connecting board 3 ispushed in the direction shown by an arrow mark E in FIG. 8 to get overthe inclined surface 42 b of the engaging member 42. Thus, theconnecting board 3 is arranged between the front wall part 4 a of theframe 4 and the vertical surface 42 a of the engaging member 42. Whenthe connecting board 3 is detached from the frame 4, the connectingboard 3 needs to get over the vertical surface 42 a of the engagingmember 42 so that the connecting board 3 can be prevented from falling.

Further, in case a connecting terminal from the external device isconnected to the terminal part 31 of the connecting board 3, when forceis externally exerted on the connecting board, for instance, when theconnecting terminal is pushed through the opening part 41, theconnecting board 3 is prevented from falling by the engaging member 42.Thus, the connecting board 3 can maintain a state that the connectingboard 3 is engaged with the frame 4 and the terminals can be moreassuredly connected.

As described above, the frame 4 is disposed in the periphery of thebattery element 2. Thus, even when the battery element 2 is notaccommodated in a plastic case, the mechanical strength and thereliability of the terminals equal to those when the plastic case isused can be maintained.

Then, as shown in an arrow mark D in FIGS. 6 and 9, a third area 53 isbent to the second area 52 in a bending line 5 b. Thus, a surfaceopposite to the side of the first area 51 for accommodating the batteryelement 2 which is united to the second area 52, that is, the secondsurface side of the battery element 2 is covered with the third area 53.

Finally, the third area 53 is united to the first area 51. The unitingis carried out by opposing the polypropylene layer sides of the thirdarea 53 and the first area 51 to each other and heat-sealing them atabout 170° C.

Thus, the battery element 2 is accommodated and sealed in the packagebody 5, and further, the connecting board 3 and the frame 4 are packedby the package body 5. Thus, the battery pack 1 as shown in FIGS. 2 and3 is completed.

In the battery pack 1 obtained in such a manner, the laminate materialof the battery element is used also as a pack outer package material.Accordingly, volume efficiency can be improved more by 10% or higherthan that obtained when the plastic case is used as an outer packagematerial. Thus, the volume density of the battery pack 1 can beimproved.

Further, the frame is disposed in the periphery of the battery element,the same mechanical strength and reliability of the terminals as thosewhen the plastic case is employed can be maintained to realize a highreliability.

The laminate material of the battery element is shared with the packagebody of the battery pack so that a design can be simplified, the batteryelement and the battery pack can be consistently produced and a processcost can be reduced. Further, a production time can be shortened toimprove productivity.

Further, parts such as a case, a tape, a label, etc, necessary when theplastic case is used are not necessary. Thus, the number of parts can bereduced and a material cost can be reduced.

Second Embodiment

FIG. 10 is a perspective view showing one structural example of abattery pack 10 to which the present invention is applied. FIG. 11 is asectional view taken along a line X₅-X₆ in FIG. 10. FIGS. 12 to 18 arediagrams for explaining a method for producing the battery pack 10.

The battery pack 10 comprises a battery element 2, a connecting board 3,a frame 4 and a package body. The battery element 2 is accommodated andsealed in the package body and further packed together with theconnecting board 3 and the frame 4 by the package body.

The battery element, the connecting board and the frame havesubstantially the same structures as those of the battery element 2, theconnecting board 3 and the frame 4 of the battery pack 1 in theabove-described first embodiment. Accordingly, these members aredesignated by the same reference numerals in the drawings and thedetailed description thereof is omitted here.

The package body for accommodating and packing the battery element 2 iscomposed of two package bodies including a first package body 6 and asecond package body 7.

The first package body 6 has a substantially rectangular form and ahousing recessed part 61 in which the battery element 2 is accommodatedis previously formed, as shown in FIG. 12. In the periphery of thehousing recessed part 61, a uniting piece 62 is provided. In one endpart in the longitudinal direction, cut-out parts 63 are formed at bothends in the direction of a short side. The first package body 6 has, asshown in FIG. 13, a laminated structure in which a polypropylene (PP)layer 64, an aluminum (Al) layer 65 and a nylon layer (Ny) 66 arelaminated in order from inside. The polypropylene layer 64 serves as auniting surface.

The second package body 7 includes, as shown in FIG. 14, at least afirst area 71 with a substantially rectangular form and a second area 72with a substantially rectangular form continuous to the direction of ashort side of the first area 71. Here, the first area 71 serves as anarea with which a first surface of the battery element 2 housed in thehousing recessed part 61 of the first package body 6 which is exposedoutside is covered. The second area 72 serves as an area with which asecond surface side of the battery element 2 is covered together withthe first package body 6. Further, in the second package body 7, cut-outparts 73 are similarly formed in parts corresponding to the cut-outparts 63 formed in the first package body 6.

The second package body 7 is made of a material harder than that of thefirst package body 6. As a material of the second package body 7, analuminum thin plate having a polypropylene layer formed in an innersurface or the like may be exemplified. The hard material is used forthe second package body 7 as an outer package body to assure a strengthand obtain an excellent impact resistance.

The structures of the first package body 6 and the second package body 7are not limited to the above-described structures and a laminate filmhaving various kinds of materials and laminated structures may beemployed. Further, a uniting method thereof is not limited to a heatsealing method.

In the present invention, the package body for sealing the batteryelement 2 is also used as an outer package material of the battery pack10 so that a plastic case is not required to improve volume efficiency.

Firstly, as shown by an arrow mark F in FIG. 12, the battery element 2is accommodated in the housing recessed part 61 that is provided in thefirst package body 6. At this time, the terminal side of the batteryelement 2 is disposed so as to be opposite to a side in which thecut-out parts 63 are formed.

Then, as shown in FIG. 14, the second package body 7 is superposed onthe first package body 6 having the housing recessed part 61 in whichthe battery element 2 is housed. Thus, the first surface of the batteryelement 2 housed in the housing recessed part 61 which is exposedoutside is covered with the first area 71 of the second package body 7.

At this time, as shown in FIG. 14, the second package body 7 is arrangedto be shifted inside an outer line of the uniting piece 62 of the firstpackage body 6.

Then, the first package body 6 is united to the first area 71 of thesecond package body 7. When the first package body 6 is united to thefirst area 71 of the second package body 7, the polypropylene surfacesof the first package body 6 and the first area 71 of the second packagebody 7 are opposed to each other in the four sides of the periphery ofthe battery element 2 housed in the housing recessed part 61 andheat-sealed at about 170° C.

At this time, as shown in FIG. 16, a pressure reducing pump 80 is usedto reduce pressure as well as a uniting. Thus, the battery element 2 iscovered with and sealed by the first package body 6 and the first area71 of the second package body 7. At this time, a cathode terminal 21 andan anode terminal 22 of the battery element 2 are sandwiched in betweenthe uniting surfaces of the first package body 6 and the first area 71of the second package body 7 to be exposed outside the package body.

Here, the pressure is reduced to suck the first package body 6. Thus, asshown in FIG. 16, the battery element 2 accommodated in the housingrecessed part 61 is drawn to have a substantially trapezoidal form inwhich the second surface side as the bottom surface side of the housingrecessed part 61 is small and the first surface side as an opening sideis large.

Subsequently, the cathode terminal 21 and the anode terminal 22 areconnected to a terminal part 31 of the connecting board 3. Then, asshown by an arrow mark G in FIG. 15, in the periphery of the batteryelement 2 accommodated in the housing recessed part 61 of the firstpackage body 6 and covered and sealed with the first area 71 of thesecond package body 7, the frame 4 is disposed from the first packagebody 6 side. The connecting board 3 having the terminal part 31 to whichthe cathode terminal 21 and the anode terminal 22 are connected isfitted to the frame 4.

The frame 4 is disposed in the periphery of the battery element 2, sothat even when the battery element 2 is not disposed in a plastic case,the same mechanical strength and reliability of the terminals as thosewhen the plastic case is used can be ensured.

As described above, the battery element 2 has a substantiallytrapezoidal shape in section under a reduced pressure. As shown in FIG.16, the side surface walls of the frame 4 are arranged in space partsformed in the peripheral edge parts of the second surface side of thebattery element 2. Thus, a dead space can be effectively utilized tomore improve volume efficiency.

Then, as shown in an arrow mark H in FIGS. 15 and 17, the second area 72of the second package body 2 is bent relative to the first area 71 in abending in a bending line. Thus, the second surface side opposed to thefirst surface of the battery element 2 accommodated in the housingrecessed part 61 of the first package body 6 and covered with the firstarea 71 of the second package body 7 is covered with the second area 72.

At this time, the uniting piece 62 of the first package body 6 is bentas shown by an arrow mark I in FIG. 16 and arranged along the frame 4disposed in the periphery of the battery element 2.

Finally, the first package body 6 is opposed and united to the secondpackage body 7.

At this time, the second package body 7 is superposed on the firstpackage body 6 under a state that the second package body 7 is shiftedfrom the first package body 6. As shown in FIGS. 14 and 16, an end part71 a in the first area 71 side of the second package body 7 is locatedinside the uniting piece 62 of the first package body 6.

Accordingly, as shown in FIGS. 17 and 18, the uniting piece 62 disposedalong the frame 4 protrudes from the first area 71 of the second packagebody 7 disposed along the frame 4 as shown by an arrow mark J. Theprotruding surface of the uniting piece 62 is opposed and united to asurface located inside when the first package body 6 is covered with thesecond area 72. That is, these surfaces are the surfaces of thepolypropylene layers of the first package body 6 and the second packagebody 7, and united to each other by opposing and heat-sealing them atabout 170° C.

Further, as shown in FIG. 18, in the second package body 7, the end part71 a of the first area 71 side is butted against and united to the endpart 72 a of the second area 72 side.

Further, also in the rear end side of the frame 4, the protrudingsurface of the uniting piece 62 is opposed and united to a surfacelocated inside when the first package body 6 is covered with the secondarea 72 in the same manner as described above.

Thus, the battery element 2 is accommodated and sealed in the packagebody including the first package body 6 and the second package body 7,and further, the connecting board 3 and the frame 4 are packed by thepackage body. Thus, the battery pack 10 as shown in FIGS. 10 and 11 iscompleted.

In the battery pack 10 obtained in such a manner, the laminate materialof the battery element is used also as the outer package material of thepack. Accordingly, volume efficiency can be improved more by 10% orhigher than that obtained when the plastic case is used as an outerpackage material. Thus, the volume density of the battery pack 10 can beimproved.

Further, the frame is disposed in the periphery of the battery element,the same mechanical strength and reliability of the terminals as thosewhen the plastic case is employed can be maintained to realize a highreliability.

The laminate material of the battery element is shared with the packagebody of the battery pack so that a design can be simplified, the batteryelement and the battery pack can be consistently produced and a processcost can be reduced. Further, a production time can be shortened toimprove productivity.

Further, parts such as a case, a tape, a label, etc, necessary when theplastic case is used are not necessary. Thus, the number of parts can bereduced and a material cost can be reduced.

Third Embodiment

Now, a battery pack shown in FIGS. 19 and 20 will be described below. Inthis battery pack, materials of a package body are different from thoseof the above-described battery packs 1 and 10.

The battery pack 100 comprises a battery element 2, a connecting board3, a frame 110 disposed in the periphery of the battery element 2, afirst package body 120 for packing an inner part of the pack, a secondpackage body 130 for packing an outer part of the pack and a fixingmember 140 for fixing the connecting board 3. In the battery pack 100,the connecting board 3 and the frame 110 are disposed in the peripheryof the battery element 2 packed by the first package body 120 and thesecond package body 130 to unite the frame 110 to the second packagebody 130. Thus, the second package body 130 serves also as an outerpackage material of the pack.

Since the battery element 2 and the connecting board 3 have thesubstantially same structures as those of the battery pack 1 accordingto the above-described first embodiment, these members are designated bythe same reference numerals in the drawings and the detailed descriptionthereof will be omitted.

The frame 110 is a frame type member with a size adapted to the outerform of the battery element 2. The frame 110 includes, as shown in FIG.21, a front wall part 110 a disposed in the terminal side of the batteryelement 2, a rear wall part 110 b disposed in a side opposite to theterminals of the battery element 2, side wall parts 110 c disposed onthe side surface parts of the battery element 2 and an upper wall part110 d. The front wall part 110 a includes opening parts 111 for exposinga terminal part 31 provided in the connecting board 3 when theconnecting board 3 is arranged and an engaging recessed part 112engaging with the below-described fixing member 140. Here, an examplethat three opening parts 111 are provided is shown. These opening parts111 can be used for, for instance, a cathode terminal 21, an anodeterminal 22 and other information terminal. However, the opening partsare not limited thereto. Further, the engaging recessed part 112 isformed in an inner surface of the front wall part 110 a and engaged withthe below-described fixing member 140.

Further, as shown in FIGS. 21 and 22, in the lower end sides of the sidewall parts 110 c of the frame 110, first step parts 113 with which theend parts of the uniting piece 122 of the first package body 120 areengaged are provided. In the upper parts of the first step parts 113,second step parts 114 with which the end parts of the uniting part 131 bof the second package body 130 are engaged are provided. In the upperside end face of the frame 110, third step parts 115 with which the endparts of the second area 132 of the second package body 130 are engagedare provided.

The first step part 113 is specifically formed by a cut-out partprovided in a corner formed by the outer surface and the bottom surfaceof the side wall part 110 c. The cut-out part is formed toward theinside of the frame 110 with the substantially same width as thethickness of the first package body 120 engaged therewith. Further, thefirst step part 113 may be formed by providing a cut-out part toward theinside of the frame 110 with a smaller width than the thickness of thefirst package body 120. In this case, the width of the first step part113 is formed so as not to expose a below-described aluminum layer 124of the first package body 120.

In the second step part 114, a cut-out part is provided to be continuousto the first step part 113. The cut-out part is formed toward the insideof the frame 110 with the substantially same width of the thickness ofthe second package body 130 engaged therewith. Further, the second steppart 114 may be formed by providing a cut-out part toward the inside ofthe frame 110 with a smaller width than the thickness of the secondpackage body 130.

Each third step part 115 is opened and provided in an inside corner parton an upper end. The third step part 115 is formed toward the outer partof the frame 110 with the substantially same width as the thickness ofthe second package body 130 engaged therewith. Further, the third steppart 115 may be formed by providing a step part toward the outside ofthe frame 110 with a smaller width than the thickness of the secondpackage body 130.

When the second step part 114 and the third step part 115 are formedwith the width smaller than the width of the second package body 130,they are formed with such a width as not to expose outside abelow-described aluminum layer 134 of the second package body 130.

In the first step parts 113 and the second step parts 114, the end partsof the uniting piece 122 of the first package body 120 are engaged withthe first step parts 113. The end parts of the uniting part 131 b of thesecond package body 130 are engaged with the second step parts 114 abovethe first step parts 113. Thus, the end parts of the uniting piece 122of the first package body 120 are shifted from the end parts of theuniting part 131 b of the second package body 130 on the side walls.Accordingly, conductive metal layers respectively forming the end partscan be prevented from coming into contact with each other to generate ashort-circuit.

Further, since the end parts of the second area 132 of the secondpackage body 130 engaged with the third step parts 115 are separatedfrom the end parts of the first area 131 of the second package body 130engaged with the second step parts 114, a short-circuit between the endparts of the second area 132 of the second package body 130 and the endparts of the first area 131 of the second package body 130 is prevented.

Further, since the first step parts 113 to the third step parts 115 areprovided in the frame 110, the end parts of the first package body 120and the end parts of the second package body 130 do not protrudeoutside. Accordingly, the battery pack 100 is prevented from externallygiving a damage due to the end parts of the package bodies.

Further, the frame 110 is disposed in the periphery of the batteryelement 2, so that the battery element 2 can be protected from theimpact of, for instance, falling or the like. The frame 110 may be madeof various kinds of plastic materials. Specially, a material having thesame quality as that of polypropylene used for the package body, thatis, polypropylene or a material having the same melting point as that ofpolypropylene may be preferably exemplified in view of the uniting tothe package body.

The first package body 120 has, as shown in FIG. 23, a substantiallyrectangular form and a housing recessed part 121 previously formed inwhich the battery element 2 is accommodated. In the periphery of thehousing recessed part 121, the uniting piece 122 to be united to thebelow-described second package body 130 is provided. In one short sideof the first package body 120, cut-out parts 123 are provided.

The first package body 120 has, as shown in FIG. 24, a laminatedstructure in which a polypropylene (PP) layer 123, an aluminum (Al)layer 124 and a nylon layer (Ny) 125 are laminated in order from inside.The polypropylene layer 123 serves as a uniting surface when the firstpackage body 120 is united to the second package body 130. The aluminumlayer 124 serves to maintain the air-tightness of the battery pack 100.The nylon layer 125 has such a strength as to withstand an externalimpact such as piercing and maintains an insulation between the outerpart of the pack and the aluminum layer 124.

The second package body 130 includes, as shown in FIG. 25, the firstarea 131 formed in a substantially rectangular shape and the second area132 with a substantially rectangular form provided continuously to oneshort side of the first area 131.

The first area 131 includes a cover part 131 a with which a firstsurface of the battery element 2 housed in the housing recessed part 121of the first package body 120 which is exposed outside is covered andthe uniting part 131 b united to the uniting piece 122 of the firstpackage body 120.

The cover part 131 a has the substantially same area as that of thefirst surface of the battery element 2. The uniting part 131 b is formedto be larger than the uniting piece 122 of the first package body 120both in the directions of a long side and a short side. The parts of theuniting part 131 b larger than the uniting piece 122 of the firstpackage body 120 serve as margin parts 131 c to be united to the sidewall parts 110 c of the frame 110. In the margin parts 131 c,below-described polypropylene layers 133 are exposed to the firstpackage body 120 side.

Thus, in the first area 131, the cover part 131 a with which the firstsurface of the battery element 2 is covered forms one main surface ofthe battery pack 100. The uniting part of the uniting piece 122 of thefirst package body 120 located in the long side of the battery element 2and the uniting part 131 b of the first area 131 forms a side surface ofthe long side of the battery pack 100 by uniting the side wall parts 110c of the frame 110 to the margin parts 131 c of the first area 131. Inthe first area 131, at both the ends of a short side opposite to a shortside to which the second area 132 is united, cut-out parts 131 d areformed.

The second area 132 is formed in a substantially rectangular shape andprovided continuously to one short side of the second package body 130.The second area 132 covers an end part opposite to an end part fromwhich the terminal part of the battery element 2 is drawn and thehousing recessed part 121 of the first package body 120. Accordingly,the second area 132 forms the side surface of the end part opposite tothe end part in which the opening parts 111 of the frame 110 of thebattery pack 100 are provided and the other main surface of the batterypack 100.

The second package body 130 is formed by laminating a resin layer madeof a resin material and a metal layer made of metal and is a laminatefilm having a laminated structure in which a polypropylene (PP) layer133 as the resin layer, an aluminum (Al) layer 134 as the metal layer onthe polypropylene layer 133 and a nylon layer (Ny) 135 as the resinlayer on the aluminum layer 134 are laminated. The polypropylene layer133 serves as a uniting surface when the first package body 120 isunited to the second package body 130.

The aluminum layer 134 serves to maintain the air-tightness of thebattery pack 100. The aluminum layer 134 employs a harder aluminummaterial than that of the aluminum layer 124 used for the first packagebody 120. As such aluminum, there is, for instance, 3004H-H18 (JapaneseIndustrial Standards: JIS H4160) material or the like. Further, as themetal layer, a layer using a material such as stainless steel, copper(Cu), nickel (Ni), iron (Fe), etc. may be provided as well as thealuminum layer 134. Here, the Vickers hardness of the aluminum layer 134is 50 Hv or higher and 100 Hv or lower.

The nylon layer 135 as the resin layer has such a strength as towithstand an external impact such as piercing and maintains aninsulation between the outer part of the pack and the aluminum layer134. Further, as the resin layer, a polyethylene terephthalate (PET)layer or a polyethylene naphthalate (PEN) layer using materials such aspolyethylene terephthalate (PET) or polyethylene naphthalate (PEN), etc.may be employed as well as the nylon layer 135.

Since the thickness of the polypropylene layer 133 is about 20 μm, thethickness of the aluminum layer 134 is about 100 μm, and the thicknessof the nylon layer 135 is about 30 μm, respectively, the total thicknessof the second package body 130 is about 150 μm.

The fixing member 140 comprises, as shown in FIG. 29, support parts 141for supporting the connecting board 3 and engaging protrusions 142provided at both outer ends of the support parts 141 and engaged withthe front wall part 110 a of the frame 110. The support parts 141 areformed in substantially U shapes to hold and support both the ends ofthe connecting board 3 between them. When the engaging protrusions 142are disposed in the frame 110, the engaging protrusions are engaged withthe engaging recessed parts 112 provided in the front wall part 110 a ofthe frame 110 and fixed in the frame 110. Accordingly, the fixing member140 is disposed in the frame 110 together with the connecting board 3 toassuredly fix the connecting board 3 by the support members 141 and theengaging protrusions 142. Further, when the thickness of the connectingboard 3 is small, for instance, when the connecting board 3 whosethickness is 4.0 mm or less is used, the fixing member 140 is especiallyeffective.

Now, a method for producing the battery pack 100 having theabove-described structure will be described below. Firstly, as shown byan arrow mark K in FIG. 23, the battery element 2 is accommodated in thehousing recessed part 121 of the first package body 120. At this time,the terminal part of the battery element 2 is drawn to the short side ofthe first package body 120.

Then, as shown in FIG. 27, the first area 131 of the second package body130 is superposed on the first package body 120 from a side in which thebattery element 2 is exposed so that the polypropylene layer 133 of thesecond package body 130 is located in the first package body 120 side.Thus, the first surface of the battery element 2 housed in the housingrecessed part 121 of the first package body 120 which is exposed outsideis covered with the first area 131 of the second package body 130. Atthis time, the second package body 130 is superposed on the firstpackage body 120 so that the second area 132 of the second package body130 is located in a short side opposite to the short side from which theterminal part of the battery element 2 is drawn. Under this state, thepolypropylene layers 133 of the margin parts 131 c provided in the firstarea 131 of the second package body 130 are exposed to the first packagebody 120 side.

Then, the first package body 120 is united to the first area 131 of thesecond package body 130. When the first package body 120 is united tothe first area 131 of the second package body 130, the polypropylenelayer 123 of the uniting piece 122 of the first package body 120 isunited to the polypropylene layer 133 of the uniting part 131 b of thefirst area 131 of the second package body 130 by heat-sealing them atabout 170° C. in the four sides of the periphery of the battery element2 housed in the housing recessed part 121 of the first package body 120.

At this time, as shown in FIG. 28, a pressure reducing pump 80 is usedto reduce pressure in a space for accommodating the battery element 2which is formed by the first package body 120 and the second packagebody 130 as well as the uniting. Thus, the battery element 2 is coveredwith and sealed by the first package body 120 and the first area 131 ofthe second package body 130. At this time, the cathode terminal 21 andthe anode terminal 22 of the battery element 2 are sandwiched in betweenthe uniting surfaces of the first package body 120 and the secondpackage body 130 to be drawn outside the package body.

Here, the pressure is reduced to suck the inner part of the housingrecessed part 121 of the first package body 120. Thus, as shown in FIG.28, the battery element 2 accommodated in the housing recessed part 121of the first package body 120 is drawn by the first package body 120 tohave a substantially trapezoidal form in section in which the secondsurface side of the battery element 2 as the bottom surface side of thehousing recessed part 121 is small and the first surface side as anopening side is large.

Subsequently, the cathode terminal 21 and the anode terminal 22 areconnected to a terminal part of the connecting board 3. Then, as shownby an arrow mark L in FIG. 29, in the periphery of the battery element 2covered and sealed with the first package body 120 and the secondpackage body 130, the frame 110 is disposed from the first package body120 side. The fixing member 140 for supporting the connecting board 3 towhich the cathode terminal 21 and the anode terminal 22 are connected isarranged in the frame 110.

At this time, the fixing member 140 is disposed in the frame 110 so thatthe engaging protrusions 142 of the fixing member 140 are engaged withthe engaging recessed parts 112 formed in the frame 110 to fix theconnecting board 3 in the frame 110. Further, the frame 110 is disposedin the periphery of the battery element 2, so that even when the batteryelement 2 is not disposed in a plastic case, the same mechanicalstrength and reliability of the terminals as those when the plastic caseis used can be ensured. As described above, the battery element 2 has asubstantially trapezoidal shape in section under a reduced pressure.Thus, as shown in FIG. 28, the side surface walls 110 c of the frame 110are arranged in space parts formed in the peripheral edge parts of thesecond surface side of the battery element 2. Accordingly, a dead spacecan be effectively utilized to more improve volume efficiency.

Then, as shown in an arrow mark M in FIGS. 29 and 30, the second area132 of the second package body 130 is bent to the second surface side ofthe battery element 2 accommodated in the housing recessed part 121 ofthe first package body 120 along a boundary relative to the first area131 and arranged on the frame 110 in the periphery of the housingrecessed part 121. Then, the second area 132 of the second package body130 with which the housing recessed part 121 of the first package body120 is covered is heat-sealed to the side wall parts 110 c of the frame110 to cover the housing recessed part 121 of the first package body 120with the second package body 130. At this time, as shown in FIG. 22, theend parts of the second area 132 of the second package body 130 abut onthe third step parts 115.

Further, at this time, the uniting parts of the uniting pieces 122 ofthe first package body 120 and the uniting parts 131 b of the first area131 of the second package body 130 are bent as shown by arrow marks N inFIGS. 28 and 29 and arranged in the side wall parts 110 c of the frame110 provided in the periphery of the battery element 2 as shown in FIG.22.

After that, the margin parts 131 c of the first area 131 of the secondpackage body 130 are heat-sealed to the side wall parts 110 c of theframe 110. As shown in FIG. 22, the uniting pieces 122 of the firstpackage body 120 abut on the first step parts 113 and the margin parts131 c of the first area 131 of the second package body 130 abut on thesecond step parts 114 so that the battery pack 100 is completed.

As described above, the margin parts 131 c of the first area 131 of thesecond package body 130 are heat-sealed to the side wall parts 110 c ofthe frame 110. Thus, the uniting pieces 122 of the first package body120 abut on the first step parts 113 and the margin parts 131 c of thefirst area 131 of the second package body 130 abut on the second stepparts 114. As a result, a short-circuit between the first package body120 and the second package body 130 is prevented.

Further, the thickness of the first step parts 113 and the second stepparts 114 is respectively substantially the same as those of the firstpackage body 120 and the second package body 130. Accordingly, the firstpackage body 120 and the second package body 130 are heat-sealed to theside wall parts 110 c of the frame 110 so that the side wall parts 110 cof the frame 110 are flush. Thus, the first package body 120 and thesecond package body 130 are prevented from being separated.

In the battery pack 100 obtained in such a manner, the second packagebody 130 made of the laminate film is used also as the outer packagematerial of the pack. Accordingly, volume efficiency can be improvedmore by 10% or higher than that obtained when the plastic case is usedas an outer package material. Thus, the volume density of the batterypack 100 can be improved.

In the battery pack 100, since the second package body 130 exposedoutside the pack is harder than the first package body 120 accommodatedin the pack, the battery element 2 is prevented from being deformed ordeteriorated in the inner part due to an external impact such as animpact owing to falling and the generation of flaws on the outer surfaceof the pack is suppressed. Accordingly, in the battery pack 100, anexternal appearance is prevented from being poor.

In the battery pack 100, when the housing recessed part 121 of the firstpackage body 120 is covered with the second area 132 of the secondpackage body 130, the second area 132 of the second package body 130 isbent to the second surface side of the battery element 2 along the shortside as the boundary relative to the first area 131. Thus, the bent partis short, so that the generation of wrinkles or the like on the bentpart is suppressed to improve an external appearance.

Further, in the battery pack 100, when the second package body 130 isunited to the frame 110, the polypropylene layers 123 and 133 thereofare heat-sealed together. Therefore, an assured and stable uniting canbe obtained in a short time by the margin parts 131 c of small areasprovided in the second package body 130.

Fourth Embodiment

Now, a battery pack 200 having two package bodies for packing the outerpart of a pack, which is different from the above-described battery pack100, will be described by referring to FIGS. 31 and 32.

The battery pack 200 comprises a battery element 2, a connecting board3, a frame 110, a first package body 210 for packing an inner part ofthe pack, a second package body 220 and a third package body 230 forpacking an outer part of the pack and a fixing member 140. In thebattery pack 200, the connecting board 3 and the frame 110 are disposedin the periphery of the battery element 2 packed by the first packagebody 210 and the second package body 220 to unite the third package body230 to the frame 110. Thus, the second package body 220 and the thirdpackage body 230 serve also as an outer package material of the pack.

Since the battery element 2, the connecting board 3 and the fixingmember 140 have the substantially same structures as the battery element2, the connecting board 3, the frame 110 and the fixing member 140 ofthe battery pack 100 according to the above-described third embodiment,these members are designated by the same reference numerals in thedrawings and the detailed description thereof will be omitted.

The first package body 210 has, as shown in FIG. 33, a substantiallyrectangular form and a housing recessed part 211 previously formed inwhich the battery element 2 is accommodated. In the periphery of thehousing recessed part 211, uniting pieces 212 to be united to thebelow-described second package body 220 are provided. In both the endsof both short sides of the first package body 210, cut-out parts 213 areformed.

The first package body 210 has the same material and the same structureas those of the first package body 120 of the above-described thirdembodiment. Accordingly, the detailed explanation thereof will beomitted.

The second package body 220 is formed in a substantially rectangularshape and includes, as shown in FIGS. 34 and 35, a cover part 221 withwhich a first surface of the battery element 2 housed in the housingrecessed part 211 of the first package body 210 which is exposed outsideis covered and uniting parts 222 to be united to the uniting pieces 212of the first package body 210.

The cover part 221 has the substantially same area as that of the firstsurface of the battery element 2. The uniting part 222 is formed to belarger than the uniting piece 212 of the first package body 210 both inthe directions of a long side and a short side. The parts of the unitingpart 222 larger than the uniting piece 212 of the first package body 120serve as margin parts 222 a to be united to the side wall parts 110 c ofthe frame 110. In the margin parts 222 a, polypropylene layers 133 areexposed to the first package body 210 side. In the second package body220, cut-out parts 223 are provided at both ends of one short side likethe first package body 210.

The second package body 220 having the above described structure isunited to the first package body 210 to cover the first surface of thebattery element 2 therewith and form one main surface of the batterypack 200. Further, the uniting parts of the uniting parts 222 of thesecond package body 220 and the uniting pieces 212 of the first packagebody 210 form side surfaces of the battery pack 200 by uniting the sidewall parts 110 c of the frame 110 to the margin parts 222 a of theuniting parts 222.

The third package body 230 is formed in a substantially rectangularshape to cover the housing recessed part 211 of the first package body210 through the frame 110 from a second surface side opposite to thefirst surface of the battery element 2. On one short side of the thirdpackage body 230, cut-out parts 231 are formed so as to correspond torecessed parts formed in the front wall part 110 a of the frame 110. Thethird package body 230 is united to the frame 110 to cover the housingrecessed part 211 of the first package body 210 therewith and form theother main surface of the battery pack 200.

The above-described second package body 220 and the third package body230 are respectively composed of resin layers and metal layers and havethe same materials and structures as those of the second package body130 of the third embodiment. Accordingly, the detailed explanationthereof will be omitted.

Now, a method for producing the battery pack 200 having theabove-described structure will be described below. Firstly, as shown byan arrow mark O in FIG. 33, the battery element 2 is accommodated in thehousing recessed part 211 of the first package body 210. At this time,the terminals of the battery element 2 are drawn to one short side ofthe first package body 210.

Then, as shown in FIG. 34, the second package body 220 is superposed onthe first package body 210 from a side in which the battery element 2 isexposed so that the polypropylene layer 133 of the second package body220 is located in the first package body 210 side. Thus, the firstsurface of the battery element 2 housed in the housing recessed part 211of the first package body 210 which is exposed outside is covered withthe second package body 220.

Then, the first package body 210 is united to the second package body220. When the first package body 210 is united to the second packagebody 220, the polypropylene layers 123 of the uniting pieces 212 of thefirst package body 210 are united to the polypropylene layers 133 of theuniting parts 222 of the second package body 220 by heat-sealing them atabout 170° C. in the four sides of the periphery of the battery element2 housed in the housing recessed part 211.

At this time, as shown in FIG. 35, a pressure reducing pump 80 is usedto reduce pressure as well as the uniting. Thus, the battery element 2is covered with and sealed by the first package body 210 and the secondpackage body 220. At this time, a cathode terminal 21 and an anodeterminal 22 of the battery element 2 are sandwiched in between theuniting surfaces of the first package body 210 and the second packagebody 220 to be drawn outside the package body.

Here, the pressure is reduced to suck the inner part of the housingrecessed part 211 of the first package body 210. Thus, as shown in FIG.35, the battery element 2 accommodated in the housing recessed part 211of the first package body 210 is drawn by the first package body 210 tohave a substantially trapezoidal form in section in which the secondsurface side of the battery element 2 as the bottom surface side of thehousing recessed part 211 is small and the first surface side as anopening side is large.

Subsequently, the cathode terminal 21 and the anode terminal 22 areconnected to a terminal part of the connecting board 3. Then, as shownby an arrow mark P in FIG. 36, in the periphery of the battery element 2covered and sealed with the first package body 210 and the secondpackage body 220, the frame 110 is disposed from the first package body210 side. The fixing member 140 for supporting the connecting board 3 towhich the cathode terminal 21 and the anode terminal 22 are connected isarranged in the frame 110.

At this time, the connecting board 3 and the fixing member 140 aredisposed together in the frame 110 so that the engaging protrusions 142of the fixing member 140 are engaged with engaging recessed parts 112formed in the frame 110 to fix the connecting board 3 to the frame 110.Further, the frame 110 is disposed in the periphery of the batteryelement 2, so that even when the battery element 2 is not accommodatedin a plastic case, the same mechanical strength and reliability of theterminals as those when the plastic case is used can be ensured. Asdescribed above, the battery element 2 has a substantially trapezoidalshape in section under a reduced pressure. Thus, as shown in FIG. 35,the side surface walls 110 c of the frame 110 are arranged in spaceparts formed in the peripheral edge parts of the second surface side ofthe battery element 2. Accordingly, a dead space can be effectivelyutilized to more improve volume efficiency.

Then, as shown in an arrow mark Q in FIG. 36, the third package body 230is disposed on the upper wall parts 110 d of the frame 110 arranged inthe periphery of the housing recessed part 211 of the first package body210 so that the polypropylene layer 133 of the third package body 230 islocated in the housing recessed part 211 side. Then, the polypropylenelayer 133 of the third package body 230 is heat-sealed to the frame 110at about 170° C. In accordance with the heat sealing process, the endparts of the third package body 230 abut on third step parts 115provided in the frame 110 so that the upper wall parts 110 d of theframe 110 are flush.

Further, at this time, the uniting parts of the uniting pieces 212 ofthe first package body 210 and the uniting parts 222 of the secondpackage body 220 are bent as shown by arrow marks R in FIG. 35 andarranged along the side wall parts 110 c of the frame 110 provided inthe periphery of the battery element 2. After that, the margin parts 222a of the second package body 220 are heat-sealed to the side wall parts110 c of the frame 110. As shown in FIG. 37, the uniting pieces 212 ofthe first package body 210 abut on first step parts 113 and the secondpackage body 220 abut on second step parts 114 in accordance with theheat sealing process so that the side wall parts 110 c of the frame 110are flush and the battery pack 200 is completed.

As described above, the margin parts 222 a of the second package body220 are heat-sealed to the side wall parts 110 c of the frame 110. Thus,the uniting pieces 212 of the first package body 210 abut on the firststep parts 113 and the end parts of the margin parts 222 a of the secondpackage body 220 abut on the second step parts 114. As a result, ashort-circuit between the first package body 210 and the second packagebody 220 is prevented. Further, the width of the first step parts 113and the second step parts 114 is respectively substantially the same asthe thickness of the first package body 210 and the second package body220. Accordingly, the first package body 210 and the second package body220 are heat-sealed to the side wall parts 110 c of the frame 110 sothat the side wall parts 110 c of the frame 110 are flush. Thus, thefirst package body 210 and the second package body 220 are preventedfrom being peeled off.

In the battery pack 200 obtained in such a manner, the second packagebody 220 and the third package body 230 made of the laminate film areused also as the outer package material of the pack. Accordingly, volumeefficiency can be improved more by 10% or higher than that obtained whenthe plastic case is used as an outer package material.

In the battery pack 200, since the second package body 220 and the thirdpackager body 230 for packing the outer part of the pack are harder thanthe first package body 210 accommodated in the pack, the battery element2 is prevented from being deformed or deteriorated in the inner part dueto an external impact such as an impact owing to falling and thegeneration of flaws on the outer surface of the pack is suppressed.Accordingly, in the battery pack 200, an external appearance isprevented from being poor.

Further, in the battery pack 200, when the second package body 220 isunited to the frame 110, the polypropylene layers 123 and 133 thereofare heat-sealed together. Therefore, an assured and stable uniting canbe obtained in a short time by the margin parts 222 a of small areasprovided in the second package body 220.

Although the battery packs according to the embodiments of the presentinvention are described above, the present invention is not limitedthereto and may be properly changed as desired within a scope of theinvention without departing the gist of the invention.

According to the present invention, the laminate material of the batteryelement is used also as the outer package material of the pack.Accordingly, volume efficiency can be improved more by 10% or higherthan that obtained when the plastic case is used as an outer packagematerial. Thus, the battery pack whose volume density is improved can berealized. Further, the parts such as the case, the tape, the label, etc.necessary when the plastic case is used are not necessary so that thenumber of parts can be reduced and the material cost can be reduced.

Further, in the present invention, the frame is disposed in theperiphery of the battery element, the same mechanical strength andreliability of the terminals obtained when the plastic case is used canbe maintained to realize the battery pack with high reliability.

Still further, in the present invention, the laminate material of thebattery element is shared with the package body of the pack, so that adesign can be simplified, the battery element and the battery pack canbe consistently produced and the process cost can be reduced. Further, aproduction time can be shortened to improve productivity.

Furthermore, in the battery pack according to the present invention, thepackage body provided outside the pack is harder than the package bodyprovided inside the pack. Thus, while the drawing characteristics of ausually soft package body for packing the battery element areeffectively utilized, the battery element can be prevented from beingdeformed or deteriorated in the inner part due to an external impactsuch as an impact owing to falling and the generation of flaws on theouter surface of the pack can be suppressed. Accordingly, in the batterypack, an external appearance can be prevented from being poor.

1. A method for producing a battery pack comprising: a first step ofhousing a battery element having a cathode, an anode, a polymerelectrolyte, and terminals being drawn from the cathode and the anode,in a recessed part of a package body, said package body having (a) firstarea having a recessed part (b) a second area contiguous to the firstarea and forming a substantially straight line between the first areaand the second area (c) a third area contiguous to the second area andforming a substantially straight second line between the second area andthe third area such that the second line is substantially perpendicularto the first line; a second step of covering the battery element withthe second area by folding the second area at a first folding edgelocated where the first area and the second area meet such that thesecond area is folded over a first surface of the first area so as tocover any exposed surface of the battery element with the second area,the third area now adjacent to the first area as a result of folding thesecond area over the first surface of the first area, and joining thefirst area to the second area; a third step of connecting the terminalsof the battery element to a connecting board having a terminal partelectrically connected to an external device, providing a frame in theperiphery of the housing recessed part in which the battery element ishoused and disposing the connecting board in the frame; a fourth step ofcovering the second surface of the first area by folding the third areaof the package body at a second folding edge located where the secondarea and the third area meet such that the third area is folded over asecond surface of the first area; and a fifth step of joining the thirdarea to the first area wherein, the packaged body is folded along thefirst folding edge so that the second area is in contact with the firstarea along a periphery of the battery element, and the packaged body isfolded along the second folding edge so that third area overlies and isin contact with an exposed surface of the first area.
 2. The method forproducing a battery pack according to claim 1, wherein while a spaceformed by the housing recessed part of the first area and the secondarea in the second step and in which the battery element is housed isunder a pressure reduced state, the first area is united to the secondarea.
 3. The method for producing a battery pack according to claim 1,wherein the package body is formed by laminating polypropylene,aluminum, nylon in order from inside, and polypropylene sides areopposed and united to each other by heat-sealing.